My rear fan bypass box!
03-16-2009, 06:16 AM
#16
Drifting
Thread Starter
Interesting. I just tried it but it didn't work. I'm not sure about everyting now since the error codes kicked in and now I don't have the time to reset them.
But it feelt like the fans worked when I left the blue dot but only up till maybe 22 degrees on the ****, then they cut out. They also ran a little longer, 20 sec compared to 10 seconds.
I'll try some new resistors.
Thomas
But it feelt like the fans worked when I left the blue dot but only up till maybe 22 degrees on the ****, then they cut out. They also ran a little longer, 20 sec compared to 10 seconds.
I'll try some new resistors.
Thomas
03-16-2009, 10:58 AM
#17
Racer
Join Date: Sep 2004
Location: Farmington, MI
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Thomas - thanx much for your diligence and reporting here. I'm very interested in finding a solution that restores total fan speed controls in cooperation with the resistors if one can be found.
03-17-2009, 01:34 PM
#18
Hi,
first remove the rear blower relay. Then install two jumpers in same place. Connect 30 to 87 and 30C to 87C, or 30 to 87C and 30C to 87. No difference. 30 and 30C are anyway connected.
No more. You can now remove temperature probe and original resistor too, if you want.
first remove the rear blower relay. Then install two jumpers in same place. Connect 30 to 87 and 30C to 87C, or 30 to 87C and 30C to 87. No difference. 30 and 30C are anyway connected.
No more. You can now remove temperature probe and original resistor too, if you want.
03-17-2009, 02:54 PM
#20
03-17-2009, 03:17 PM
#22
What can I say? Is so, that this solution gives to CCU info for working.OK, I´m not author for this solution. It is used by germany cars many years.
And I tried it and it´s was working. When I looked wiring diagram, there was not easy to find, why so easy solution will work and I have not wiring diagram of CCU.
So sorry, but I can not educate you.
03-17-2009, 04:31 PM
#23
Drifting
Thread Starter
Aha.....you have to do a double-jump! I'll try that tomorrow because today I had no luck with some different tricks.
Stevepaa: Didn't you get my answer about the what the bypass does?
Stevepaa: Didn't you get my answer about the what the bypass does?
03-17-2009, 05:53 PM
#25
Burning Brakes
I wonder if the jumper method will work on early (89 and 90) 964's. I have a replacement CCU now, so will not be able to test. (The new/used CCU fixed one of my servo's, however one still does not work.)
03-18-2009, 05:22 AM
#26
Drifting
Thread Starter
Strange...but here it is again:
In order to reduce weight the cup cars and later the 993 RS had the rear blower deleted. Instead you just have a simple pipe that directs the hot air from the engine fan down through the heating system. On race cars you often even skip this pipe and then you have no heat at all.
If you delete the rear blower you have to trick the CCU to believe that the blower is still there, otherwise it will detect an error and it shuts down the front blowers to. So this is what all this fuzz is about!
But as said in the start, it's only about reducing weight.
In order to reduce weight the cup cars and later the 993 RS had the rear blower deleted. Instead you just have a simple pipe that directs the hot air from the engine fan down through the heating system. On race cars you often even skip this pipe and then you have no heat at all.
If you delete the rear blower you have to trick the CCU to believe that the blower is still there, otherwise it will detect an error and it shuts down the front blowers to. So this is what all this fuzz is about!
But as said in the start, it's only about reducing weight.
03-18-2009, 06:59 AM
#27
Drifting
Thread Starter
OK, a new update:
I just tried the "double jumping" wiht no other resistors and it works, but......
If you turn up the heat on fan speed 4 the fans cuts out for 2 seconds, after 8 seconds, then they go on again on full speed but you can here on the sound that the speed is maybe 10% slower. I can't say if this is due to a servo that changes position or if it are the fan engines. If you push the defrost button it's the same thing. It works, but the fans cuts out for 2 seconds.
The scantool still says error 43 and 46 which means fan speed 1 and 2 in the rear blower.
So if you can live with the 2 seconds hesitation on fan speed 3&4 when you turn on the heat this is so far the most simple soloution. No need for buying resistors.
Roolingjack: Do you have the same hesitation?
It would be interesting to see if this fix works for older cars to!
I just tried the "double jumping" wiht no other resistors and it works, but......
If you turn up the heat on fan speed 4 the fans cuts out for 2 seconds, after 8 seconds, then they go on again on full speed but you can here on the sound that the speed is maybe 10% slower. I can't say if this is due to a servo that changes position or if it are the fan engines. If you push the defrost button it's the same thing. It works, but the fans cuts out for 2 seconds.
The scantool still says error 43 and 46 which means fan speed 1 and 2 in the rear blower.
So if you can live with the 2 seconds hesitation on fan speed 3&4 when you turn on the heat this is so far the most simple soloution. No need for buying resistors.
Roolingjack: Do you have the same hesitation?
It would be interesting to see if this fix works for older cars to!
03-18-2009, 01:15 PM
#29
OK, a new update:
I just tried the "double jumping" wiht no other resistors and it works, but......
If you turn up the heat on fan speed 4 the fans cuts out for 2 seconds, after 8 seconds, then they go on again on full speed but you can here on the sound that the speed is maybe 10% slower. I can't say if this is due to a servo that changes position or if it are the fan engines. If you push the defrost button it's the same thing. It works, but the fans cuts out for 2 seconds.
The scantool still says error 43 and 46 which means fan speed 1 and 2 in the rear blower.
So if you can live with the 2 seconds hesitation on fan speed 3&4 when you turn on the heat this is so far the most simple soloution. No need for buying resistors.
Rollingjack: Do you have the same hesitation?
It would be interesting to see if this fix works for older cars to!
I just tried the "double jumping" wiht no other resistors and it works, but......
If you turn up the heat on fan speed 4 the fans cuts out for 2 seconds, after 8 seconds, then they go on again on full speed but you can here on the sound that the speed is maybe 10% slower. I can't say if this is due to a servo that changes position or if it are the fan engines. If you push the defrost button it's the same thing. It works, but the fans cuts out for 2 seconds.
The scantool still says error 43 and 46 which means fan speed 1 and 2 in the rear blower.
So if you can live with the 2 seconds hesitation on fan speed 3&4 when you turn on the heat this is so far the most simple soloution. No need for buying resistors.
Rollingjack: Do you have the same hesitation?
It would be interesting to see if this fix works for older cars to!
I turned **** to position 1, 2, 3 and 4, there was no cuts. It blows continously at any blowers speed.
I swiched defroster button in-out-in..., it goes momentally in and blowers works without any cuts in higher speed.
I tried several different positions between temperature and blowers speed, but have not get no cuts by front blowers.
03-18-2009, 01:22 PM
#30
Do two jumpers. Reconnect plug by rear blower. Remove rear blower relay. Put two jumpers in place relay and test it.
Then we can get some info about MY 91 cars too.